Vertical allies in air purification: evaluating climbers for particulate matter post-rainfall retention

The increase in particulate matter (PM) pollution in urban areas poses a serious threat to public health, making sustainable green infrastructure an important strategy for mitigation efforts. This study evaluated 14 different species of climbers for their capacity to accumulate and retain PM under the rainfall, with particular attention to the influence of leaf morphology variations. Field experiments combined with simulated rainfall were used to assess three PM categories: washed-off particles (_RWPM), particles that remained on leaf surfaces (_SPM), and those entrapped in epicuticular waxes (_WPM) post-rainfall. Significant interspecific variation was recorded in both total PM accumulation and the distribution of particular categories. Campsis radicans 'Ursynów' showed the highest total PM accumulation, indicating strong long-term retention potential. Higher PM accumulation was linked to traits such as raised venation and serrated margins. The results demonstrate that in vertical greenery systems, climbing plants can serve as a sustainable element to support urban air-quality improvement. Nevertheless, a successful outcome depends on species selection suited to on-site (context-dependent) application. Species capable of strong PM retention suit highly impervious environments, while lower retention species can be strategically recommended on biologically active surfaces (soil with plants), providing esthetics and atmospheric pollutant removal benefits.